The really interesting thing about Batman is that he's the same archetype as Darth Vader and the figure we used to call Satan. A few hundred years ago, the Devil's other name was the Black Man, and they said he flew like a bat.
The archetype we call Satan, of course, once went by the name of Pan.
The goatlike features commonly attributed to the devil derive from the Greek pastoral deity Pan, who was half man, half goat. I have here a picture of a sixth-century Coptic ivory carving of Pan, and if you take away the pipes and give him a pitchfork, you're looking at the devil, complete with cloven hooves, hairy legs, horns, and beard. Oh, and prominent genitals, too.
The phallic aspects tend to get airbrushed out of the modern picture of ol' Scratch, but let's not kid ourselves. When Christian artists pondered the most dangerous and subversive of the deadly sins, they weren't thinking of securities fraud. It was only natural that they should seize on the frankly sexual figure of Pan. (I'm thinking here of Pan-as-old-lech, not the romanticized Disney version.) I mean, if you want a truly disturbing portrait of wickedness, what are you going to pick up on, mass murder? Too alien. Whereas sexual license . . . I'm not pointing any fingers, but this is a topic to which a lot of us can relate. Pan also had the advantage of being pagan, and since time immemorial the gods of one age have been the demons of the next.
These guys don't really come and go so much as they swap names like they were playing musical chairs.